Tearing strip container



Jan. 28, 1964 E. w. KAISER ETAL TEARING STRIP CONTAINER Filed March 13, 1962 A flaw mi a W 5? 4 h 0 M Rmw M United States Patent 3,119,514 TEARING STRIP CONTAINER Edward William Kaiser, Palatine, and Harlen Edgar Wilkinson, Crystal Lake, 111., assignors to American Can Company, New York, N.Y., a corporation of New Jersey Fiied Mar. 13, 1962, Ser. No. 179,436 Claims. (Cl. 220-54) This invention relates to tearing strip containers of the type having a circumferential detachable tearing strip set 01f by spaced score lines adjacent an end of the container body. Specifically, the invention relates to an improvement in the side seam construction wherein the lapped margins of the side seam coinciding with the tongue end of the tearing strip are welded together in superposed relation but otherwise weakened to facilitate clean and even detachment of the strip from the container.

In tearing strip containers of the type herein described, the tearing strip defined by spaced score lines encircling the container body normally extends across the side seam and terminates in a free end or tongue which accommodates an opening key. The side seam may be of the locking and lap construction wherein that length of the side seam which extends across the tearing strip as well as the extreme end lengths which ultimately are curled into the double end seams are simple lapped construction. This reduces the thicknesses of rnetal at the curled ends and, of course, provides a tearing strip construction in the seam area which is readily detachable. These lapped margins are customarily filled with solder or other sealants to provide a completely hermetic container.

These lapped and solder-filled portions of the side seam have been a source of occasional ditficulty in effecting a perfect seal. Voids and minute openings detected in these joints have been attributed partly to imperfect soldering. Moreover, the subsequent working of the metal in or near the region of these lapped margins in flanging the container body and in double seaming the ends to the body create adverse strain in the soldered joint, frequently causing the solder bond to fail and thereby be susceptible to leakage. A solution to this problem was suggested in the early U.S. Patent No. 1,542,662, wherein is taught the spot welding of the lapped portions of the side seam to hold the lapped margins immovable in superposed relation.

In reclosure containers of the type disclosed in US. Patent No. 1,750,251, the presence of an annular beaded or curled portion in the body wall directly below the tearing strip represents a considerable working of the metal. This working also places undue strain on the solder bond in the tearing strip area of the side seam, perhaps even in excess of that caused by flanging and double seaming the end. In addition, it is frequently desirable to use tearing strips of substantial width in reclosure container constructions, which complicates even more the problem of effecting a perfect solder bond in the lap seam. For these reasons, it has been found practicable in some instances to place a spot weld in the tearing strip scam area itself so as to lock the lapped margins together. This spot weld may be used alone or in addition to the spot welds in the lapped portions at the seam extremities.

Although the weld area is small and does not seriously disrupt the normal peeling of the tearing strip during initial detachment, it has been found that a portion of the tearing strip itself will tear out and adhere to the underlying margin. This torn out portion often occurs in the form of a jagged sliver of metal which remains firmly anchored to the container by the spot weld, creating a rather unsightly and hazardous projection which could cause injury to the consumer.

An object of this invention therefore is to overcome the above-mentioned problems associated with welded lap seam tearing strip containers.

Another object is to provide a welded lap seam tearing strip container construction wherein the tearing strip may be evenly and neatly detached from the container.

Still another object is to provide a tearing strip container construction wherein the lapped margins of the side scam in the tearing strip region may be spot welded together and still permit easy and neat detachment of the tearing strip.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

These objects are accomplished by providing a construction wherein the tearing strip immediately adjacent the welding lapped margins is intentionally weakened either by forming a small score line, slit or hole in the tearing strip to one side of the weld in the direction of tear, so that as the strip is detached from the container, that portion of the tearing strip which is secured by the weld will tear into the weakening and break away, thereby terminating the tearing of this portion before it has developed into an elongated sliver of jagged metal.

Referring to the drawings:

FIGURE 1 is a perspective view of a container embodying the instant invention;

FIGURE 2 is a fragmentary perspective view of a container illustrating the undesirable feature to be overcome by this invention;

FIGURE 3 is a fragmentary perspective view similar to FIGURE 2 but showing the improvement obtained by the instant invention;

FIGURE 4 is a fragmentary enlarged sectional view taken substantially along lines 4-4 of FIGURE 1 but with parts broken away, showing the preferred form of the invention;

FIGURE 5 is a fragmentary enlarged sectional view taken substantially along lines 55 of FIGURE 1;

FIGURE 6 is a fragmentary perspective view similar to FIGURE 1, illustrating an alternate embodiment of the invention;

FIGURE 7 is a fragmentary enlarged sectional view taken substantially along lines 77 of FIGURE 6.

As a preferred or exemplary form of the instant invention, FIGURE 1 shows a container generally designated 10 comprising a tubular body 11 having metal ends 12, 12 double seamed thereto in the conventional manner. The container is illustrated as having a conventional lock and lap side seam 13, with those portions of the side seam extending across the tearing strip and into the double seams being a lap seam construction. It will be understood, however, that the side seam construction illustrated herein is for purposes of example and not restriction, other forms of side seam construction being within the purview of this invention.

A tearing strip 14 set off by spaced score lines 15 encircling the container body adjacent one end provides detachable means for opening the container. The tearing strip terminates in a tongue 16 projecting freely beyond lap seam 13 for accommodating the usual opening key 17. In the form of container illustrated, an annular bead or infolded portion 118 may be formed in the body 11 immediately below lower score line 15 to provide a smooth protective surface shielding the raw metal edge remaining after tearing strip '14 is detached. The construction and function of the head 18 is shown and described more fully in United States Patent No. 3,055,539 on Metal Container, issued on September 25, 1962 in the name of Walter F. Pillnik.

The lapped marginal edges of the body in the side seam 13 coinciding with the tearing strip are welded together as at :19 in immovable or locked superposed relation. Preferably, the lapped margins are spot welded intermediate the score lines 15, thereby locking the two thicknesses of metal so that the film of solder or like sealant placed in the lap seam to completely seal the seam will not be affected by subsequent working of the metal either above or below the tear strip. FIGURES 4 and 5 best illustrate this welded lap construction, showing the margins of the can body which constitute the lap seam at the tongue end of tearing strip 14 locked together by spot weld 19 and sealed with a thin film of solder 20 fused into the seam between the lapped margins.

FIGURE 2 shows tearing strip 14 partially detached from container '10 and illustrates the problem which the instant invention overcomes. As described hereinbefore, spot weld 1 does not appreciably interfere with the peeling of the tear strip away from the side seam as it is wound on the key 17; but because of its relatively high strength does frequently cause a portion of the tearing strip to tear away and remain fast to the underlying margin in the seam. This creates a jagged sliver-like segment of metal 21 which is not only unsightly but also a potential hazard to the consumer because of its dangerous jagged torn edges. Moreover, the possibility exists that due to the irregular pattern of tear as sliver 21 is formed, it could lead into the score lines and thereby disrupt normal removal of the tearing strip.

To prevent the formation of the sliver 21, the area of the tearing strip immediately adjacent to one side of the spot weld 19 in the direction of strip detachment is intentionally weakened. Preferably, this is accomplished by piercing or cutting a small opening or slit 22 in the tearing strip to one side of the weld but within the lap area so that as the strip is peeled away from the side scam, the torn-out portion which would normally form sliver 21 instead tears into slit 22 and terminates. Thus, the wouldbe sliver breaks away from the strip before it has had a chance to reach appreciable size. As shown in FIGURE 3, only a small stub of metal 21a remains attached to the spot weld .19.

The closer that slit 22 is placed to the spot weld the better, and it should be of sufiicient size to correspond to the weld although not so large as to unduly weaken the tearing strip to a point of fracture. To fully seal the side seam against leaks, slit 22 may be filled with solder, as illustrated in FIGURES 4 and 5; or it may be provided that when solder film is applied between the lapped margins, sufiicient solder will flow into the slit 22 to fully seal the seam.

An alternate embodiment of the invention is illustrated in FIGURES 6 and 7. Instead of the opening or slit 22, a short indentation or score line 23 is formed in the surface of the tearing strip 14- along side weld 19. This indentation is of sufiicient length and depth to eifectively weaken the tearing strip immediately adjacent the weld so that any portion of the strip which tends to remain with the weld when the strip is detached will fracture and break away along the score line. The score line 23 may be on either the inside or outside surface of the tearing strip, but preferably is inside closer to the weld nugget for greater elfectiveness. In either case, it will be seen that the solder film 20 in the seam need not necessaxily fill the indentation since the metal is not pierced completely through.

It can be seen that both the slit 22 and score line 23 are within the lap portion of the side seam 13. Such a construction is virtually necessary when using the slit 22 to avoid having an aperture communicating with the interior of the can. Even though it would be theoretically possible to fill such a communicating aperture with solder and thereby seal the same, it would be exceedingly diflicult if not impossible to perform such an operation con- All does not extend through the can body Wall, score line 23 could be located between the spaced score lines 15 beyond the lap area in the direction of strip detachment. However, to keep the stub of metal attached to the Weld spot as small as possible, and to retain the stub in a non-hazardous location within the lap area, it is preferred that the score line 23, as with the slit 22, be located within the tear strip lap area.

It is thus apparent that by means of the instant invention an objectionable jagged sliver is prevented from forming during the opening of a tear strip can wherein the lapped tongue area of the tear strip is welded. The wealtened area minimizes any increased resistance to removing the tear strip occasioned by the weld spot by causing the tear strip to break free of the weld spot closely adjacent thereto.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

We claim:

1. In a tearing strip container having a detachable tearing strip set of]? by score lines and terminating in a lap seam, the improvement comprising inner and outer lapped margins welded in locked relation intermediate said score lines in said seam, and a weakened portion in said outer margin adjacent the weld area of the scam in the direction of strip detachment to provide for neat and instant severance of the tear-ing strip from the welded portions of said margins, said weakened portion extending transversely of said tear strip with the ends thereof spaced from said score lines.

2. The container described in claim 1 wherein said lapped margins comprise a portion of the side seam of said container and are locked together by a spot weld intermediate said score lines.

3. In a soldered lock and lap side seam container having a circumferential detachable tearing strip set off by score lines terminating in said seam, the improvement comprising spot welded inner and outer lapped margins in said seam intermediate said score lines, and a transverse line of weakening in said outer margin immediately adjacent the welded area of said seam in the direction of strip detachment to provide a line of severance for neat and instant separation of said tearing strip from the welded portions of said margins, said transverse line of weakening being of such a length that its ends terminate short of contact with said score lines.

4. In a tearing s-tri-p container having a detachable tearing strip set off by score lines and terminating in a lap seam, the improvement comprising inner and outer lapped margins welded in locked relation intermediate said score lines in said seam, said outer lap having an opening formed therein adjacent the weld area of the seam in the direction of strip detachment to provide for neat and instant severance of the tearing strip fro-m the Welded portions of said margins.

5. The container described in claim 4 wherein said lapped margins have a film of solder fused therebetween which extends into and at least partially fills said opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,335,268 Erb Nov. 30-, 1943 2,753,075 Geertsen July 3, 1956 2,818,194 Pargels Dec. 31, 1957 

1. IN A TEARING STRIP CONTAINER HAVING A DETACHABLE TEARING STRIP SET OFF BY SCORE LINES AND TERMINATING IN A LAP SEAM, THE IMPROVEMENT COMPRISING INNER AND OUTER LAPPED MARGINS WELDED IN LOCKED RELATION INTERMEDIATE SAID SCORE LINES IN SAID SEAM, AND A WEAKENED PORTION IN SAID OUTER MARGIN ADJACENT THE WELD AREA OF THE SEAM IN THE DIRECTION OF STRIP DETACHMENT TO PROVIDE FOR NEAT AND INSTANT SEVERANCE OF THE TEARING STRIP FROM THE WELDED PORTIONS OF SAID MARGINS, SAID WEAKENED PORTION EXTENDING TRANSVERSELY OF SAID TEAR STRIP WITH THE ENDS THEREOF SPACED FROM SAID SCORE LINES. 